Many methods for removal of microorganisms and compounds from liquids, and in particular wastewater, are known and practiced. For the purposes herein, the term “wastewater” is meant to encompass all effluent from any industrial, domestic, or other process where the effluent contains a substantial amount of water plus microorganisms and/or dissolved chemicals, organic solids, or inorganic solids. Known methods for removing these constituents (hereinafter “treatment”) from wastewater are too diverse and numerous to be adequately summarized herein. However, all such methods have limitations related to the specific physical and chemical activity utilized and the liquid stream being treated. Most commercially available methods either require a large and complex apparatus, or are very expensive to purchase and/or to operate, require large amounts of energy, or create large amounts of waste byproducts that are either difficult to handle and/or are very expensive to dispose of.
Certain liquid streams from a range of industrial, agricultural and food processing, and domestic sources are particularly difficult to treat to achieve applicable chemical- and/or biological specific water quality objectives required for discharge, reuse, or further processing. Example chemicals in “industrial” liquid streams includes: various petroleum hydrocarbons that frequently contaminate ambient water (surface and/or groundwater) during oil and gas exploration, production, refining and/or distribution; various petroleum hydrocarbons, inorganic geochemicals and additives in flow back and produced water (frac water) from oil and gas well hydraulic fracturing operations; various inorganic chemicals in wastewater from mining operations; a range of organic and/or inorganic chemicals in wastewaters from various other manufacturing processes. Example chemicals in “agricultural and food processing” liquid streams includes: chemicals inadvertently added to ambient water (surface and groundwater) notably nitrogenous compounds (e.g., nitrate, nitrite and ammonia) and pesticides from long-term land application; chemicals and/or microorganisms (e.g., coliforms) in animal waste runoff from confined animal facilities (CAFs); hydrocarbons of biological origin in wastewaters from food processing and meat packing facilities. Example chemicals associated with “domestic” liquid streams includes: a wide range of chemicals associated with pharmaceuticals and personal care products (PPCPs) in greywater from publically owned treatment works (POTW) facilities; microorganisms, human waste products, and PPCPs and other chemicals in blackwater (septage) from private septic systems. Such liquid streams are particularly amendable to treatment using aspects of the present invention.
The term “industrial wastewater” as used herein shall include wastewaters and polluted ambient water (surface and groundwater) associated with: petroleum exploration, production, refining and distribution; chemical manufacturing and processing plants; semiconductor and electronics manufacturing; mining operations; other waste streams substantially equivalent to these specifically listed waste streams. The term “agricultural and food processing wastewater” as used herein shall include wastewaters and polluted ambient water (surface and groundwater) associated with confined animal facilities (CAFs) such as dairy, swine, beef, poultry, and aquaculture operations; food processing and production operations, and slaughterhouse and meat packing operations; other waste streams substantially equivalent to these specifically listed waste streams. The term “domestic wastewater” as used herein shall include both greywater (wastewater not containing human waste) and blackwater (wastewater containing human waste); other waste streams substantially equivalent to these specifically listed waste streams.
Removal of salts from brackish water and seawater is currently accomplished through either distillation or reverse osmosis. While these methods are effective, energy requirements and therefore costs are high, preventing widespread use. Methods have been developed to reduce energy costs through use of waste-heat to heat water in distillation or to pretreat water to remove scaling compounds in advance of reverse osmosis treatment. However, alternative methods for removing salts at low energy cost have not been proven effective to date.
There is a need for liquid treatment processes that are capable of removing these difficult dissolved chemicals in a cost-effective manner and that have a broad range of application and use conditions. In addition, the size and complexity of the associated equipment is an important factor in the utility and application of such methods.
The use of oxidizers to sanitize and/or reduce the oxygen demand of domestic, animal, and industrial waste streams is commonplace, with the addition of chlorine the most common method. Biological methods are routinely used to reduce Biological Oxygen Demand (“BOD”) and Chemical Oxygen Demand (“COD”) from these waste streams. Such systems require induction and maintenance of bacterial growth and separation of large amounts of solid waste.
Sonication of liquids is used most commonly in jewelry and parts cleaning. It is also used to induce or accelerate chemical processes in the chemical and pharmaceutical industries. Sonication methods have not heretofore been applied commercially to wastewater treatment as herein presented and claimed.
The addition of nucleating agents to liquids is commonly used in industrial processes to promote precipitation and crystallization. However, nucleating agents are not commonly used in wastewater treatment, due in part to the relatively low concentration of the target compounds in solution and the low efficiency of the precipitation reaction. Methods for improving nucleation efficiency are needed.
Adsorption processes are commonly used in a wide range of industrial processes and waste treatment applications, including removal and/or concentrating of dissolved compounds. Numerous dissolved compounds are resistant to adsorption, due to the specific ion characteristics and the lack of affinities of known adsorbents. Examples of such compounds are most salts, nitrates, nitrites, ammonia, some metals, inorganic oxides, and some hydrocarbons. Methods for improving adsorption characteristics for refractory compounds are therefore needed.